git@vger.kernel.org mailing list mirror (one of many)
 help / color / mirror / code / Atom feed
From: Johannes Sixt <j6t@kdbg.org>
To: Phillip Wood <phillip.wood123@gmail.com>
Cc: Atharva Raykar <raykar.ath@gmail.com>,
	git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>
Subject: Re: [GSOC][PATCH] userdiff: add support for Scheme
Date: Mon, 5 Apr 2021 19:58:28 +0200	[thread overview]
Message-ID: <01f17458-3d99-d4f5-aee8-0f77f73063d2@kdbg.org> (raw)
In-Reply-To: <61622cda-3ce5-7cd9-acd6-54906297500c@gmail.com>

Am 05.04.21 um 12:04 schrieb Phillip Wood:
> Hi Atharva
> 
> On 30/03/2021 11:22, Atharva Raykar wrote:
>>
>>
>>> On 30-Mar-2021, at 12:34, Atharva Raykar <raykar.ath@gmail.com> wrote:
>>>
>>>
>>>
>>>> On 29-Mar-2021, at 15:48, Phillip Wood <phillip.wood123@gmail.com>
>>>> wrote:
>>>>
>>>> Hi Atharva
>>>>
>>>> On 28/03/2021 13:23, Atharva Raykar wrote:
>>>>> On 28-Mar-2021, at 05:16, Johannes Sixt <j6t@kdbg.org> wrote:
>>>>> [...]
>>>>>>> diff --git a/t/t4018/scheme-local-define
>>>>>>> b/t/t4018/scheme-local-define
>>>>>>> new file mode 100644
>>>>>>> index 0000000000..90e75dcce8
>>>>>>> --- /dev/null
>>>>>>> +++ b/t/t4018/scheme-local-define
>>>>>>> @@ -0,0 +1,4 @@
>>>>>>> +(define (higher-order)
>>>>>>> +  (define local-function RIGHT
>>>>>>
>>>>>> ... this one, which is also indented and *is* marked as RIGHT.
>>>>> In this test case, I was explicitly testing for an indented '(define'
>>>>> whereas in the former, I was testing for the top-level
>>>>> '(define-syntax',
>>>>> which happened to have an internal define (which will inevitably
>>>>> show up
>>>>> in a lot of scheme code).
>>>>
>>>> It would be nice to include indented define forms but including them
>>>> means that any change to the body of a function is attributed to the
>>>> last internal definition rather than the actual function. For example
>>>>
>>>> (define (f arg)
>>>> (define (g x)
>>>>    (+ 1 x))
>>>>
>>>> (some-func ...)
>>>> ;;any change here will have '(define (g x)' in the hunk header, not
>>>> '(define (f arg)'
>>>
>>> The reason I went for this over the top level forms, is because
>>> I felt it was useful to see the nearest definition for internal
>>> functions that often have a lot of the actual business logic of
>>> the program (at least a lot of SICP seems to follow this pattern).
>>> The disadvantage is as you said, it might also catch trivial inner
>>> functions and the developer might lose context.
>>
>> Never mind this message, I had misunderstood the problem you were
>> trying to
>> demonstrate. I wholeheartedly agree with what you are trying to say, and
>> the indentation heuristic discussed does look interesting. I shall have a
>> glance at the RFC you linked in the other reply.
>>
>>> The disadvantage is as you said, it might also catch trivial inner
>>> functions and the developer might lose context.
>>
>> Feel free to disregard me misquoting you here. You did not say that (:
>>
>>> Another problem is it may match more trivial bindings, like:
>>>
>>> (define (some-func things)
>>>   ...
>>>   (define items '(eggs
>>>                   ham
>>>                   peanut-butter))
>>>   ...)
>>>
>>> What I have noticed *anecdotally* is that this is not common enough
>>> to be too much of a problem, and local define bindings seem to be more
>>> favoured in Racket than other Schemes, that use 'let' more often.
>>>
>>>> I don't think this can be avoided as we rely on regexs rather than
>>>> parsing the source so it is probably best to only match toplevel
>>>> defines.
>>>
>>> The other issue with only matching top level defines is that a
>>> lot of scheme programs are library definitions, something like
>>>
>>> (library
>>>     (foo bar)
>>>   (export ...)
>>>   (define ...)
>>>   (define ...)
>>>   ;; and a bunch of other definitions...
>>> )
>>>
>>> Only matching top level defines will completely ignore matching all
>>> the definitions in these files.
>>
>> That said, I still stand by the fact that only catching top level defines
>> will lead to a lot of definitions being ignored. Maybe the occasional
>> mismatch may be worth the gain in the number of function contexts being
>> detected?
> 
> I'm not sure that the mismatches will be occasional - every time you
> have an internal definition in a function the hunk header will be wrong
> when you change the main body of the function. This will affect grep
> --function-context and diff -W as well as the normal hunk headers. The
> problem is there is no way to avoid that and provide something useful in
> the library example you have above. It would be useful to find some code
> bases and diff the output of 'git log --patch' with and without the
> leading whitespace match in the function pattern to see how often this
> is a problem (i.e. when the funcnames do not match see which one is
> correct).

--function-context is just one application of the function matcher. To
work properly with nested function definitions, it would have to
understand the nesting. But it does not; there is nothing that we can do
about it without a proper language parser. Therefore, the argument that
the matcher does not work well with --function-context for nested
functions is of little relevance.

IMO, the primary concern should be whether the matcher decorates hunk
contexts sufficiently well.

-- Hannes

  reply	other threads:[~2021-04-05 17:58 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-27 17:39 [GSOC][PATCH] userdiff: add support for Scheme Atharva Raykar
2021-03-27 22:50 ` Junio C Hamano
2021-03-27 23:09   ` Junio C Hamano
2021-03-28  3:16     ` Ævar Arnfjörð Bjarmason
2021-03-28  5:37       ` Junio C Hamano
2021-03-28 12:40       ` Atharva Raykar
2021-03-29 10:08         ` Phillip Wood
2021-03-30  6:41           ` Atharva Raykar
2021-03-30 12:56             ` Ævar Arnfjörð Bjarmason
2021-03-30 13:48               ` Atharva Raykar
2021-03-28 12:45     ` Atharva Raykar
2021-03-28 11:51   ` Atharva Raykar
2021-03-28 18:06     ` Junio C Hamano
2021-03-29  8:12       ` Atharva Raykar
2021-03-29 20:47         ` Junio C Hamano
2021-03-29 10:12     ` Phillip Wood
2021-03-27 23:46 ` Johannes Sixt
2021-03-28 12:23   ` Atharva Raykar
2021-03-29 10:18     ` Phillip Wood
2021-03-29 10:48       ` Johannes Sixt
2021-03-29 13:12         ` Ævar Arnfjörð Bjarmason
2021-03-29 14:06           ` Phillip Wood
2021-03-30  7:04       ` Atharva Raykar
2021-03-30 10:22         ` Atharva Raykar
2021-04-05 10:04           ` Phillip Wood
2021-04-05 17:58             ` Johannes Sixt [this message]
2021-04-06 12:29             ` Atharva Raykar
2021-04-06 19:10               ` Phillip Wood
2021-04-03 13:16 ` [GSoC][PATCH v2 0/1] userdiff: add support for scheme Atharva Raykar
2021-04-03 13:16   ` [GSoC][PATCH v2 1/1] " Atharva Raykar
2021-04-05 10:21     ` Phillip Wood
2021-04-06 10:32       ` Atharva Raykar
2021-04-08  9:14   ` [GSoC][PATCH v3 0/1] " Atharva Raykar
2021-04-08  9:14   ` [GSoC][PATCH v3 1/1] userdiff: add support for Scheme Atharva Raykar
2021-04-12 23:04     ` Junio C Hamano

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: http://vger.kernel.org/majordomo-info.html

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=01f17458-3d99-d4f5-aee8-0f77f73063d2@kdbg.org \
    --to=j6t@kdbg.org \
    --cc=git@vger.kernel.org \
    --cc=gitster@pobox.com \
    --cc=phillip.wood123@gmail.com \
    --cc=raykar.ath@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

	https://80x24.org/mirrors/git.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).